Urea amidolyase is an ATP dependent, HCO3 requiring, biotin containing, urea cleaving enzyme system found in certain fungi and algae. The proposed research would be represented by the following points: 1. Purification of the Chlamydomonas reinhardi urea amidolyase enzymes to homogeneity; 2. Characterization of the Candida utilis and the C. reinhardi urea amidolyase enzymes as to molecular weight, amino acid analysis, biotin content, polysaccharide content, reactions catalyzed, and antigenic relatedness; 3. Demonstration, isolation and characterization of subunits as to molecular weight, amino acid composition, antigenic relatedness, N and C terminal amino acid sequences, peptides, amino acid sequences around labelled sites.